I abused the bug where you can re-enter the vending machine to buy the same items again and again to go absolutely god-mode and beat the game.
That was fun.
Well, I was playing the web build on a latest Firefox.
The bug I'm describing is where after the end of the round, I would enter the vending machine, buy e.g. the top left item which will disable buying that item again. I would then exit the vending machine and re-open the vending machine, at which point all four items will be available for purchase again.
So I would keep buying the same items, sometimes more than 10 times, by exiting and entering the vending machine. I had assumed this was just a missed case in your gameplay code, but not sure if it was dependent on my browser.